In recent years, light control devices are proposed which include materials having an electro-optic effect such as, for example, lead lanthanum titanate zirconate (PLZT). PLZT is transparent ceramics having a composition of (Pb1-yLay)(Zr1-xTix)O3. The “electro-optic effect” is a phenomenon of a change in refractivity due to polarization generated in a substance to which an electrical field is applied. Using the electro-optic effect, the phase of light penetrating a material having the electro-optic effect can be changed by turning the applied voltage on and off. Hence, the light modulation materials having the electro-optic effect can be applied to the light control devices such as light shutters (see Non patent Citation 1).
In applications of such light shutters and the like to the light control devices, PLZT have been widely used in bulk. However, it is difficult for the light shutters using bulk PLZT to comply with requests for miniaturization, integration, reduction in operating voltage or cost, and the like. Moreover, the bulk method for manufacturing the bulk PLZT includes a step of processing at a high temperature not less than 1000° C. after mixing metal oxides as raw materials. In the case of applying the bulk method to an element formation process, therefore, many restrictions are placed on selection of the materials, element structures, and the like.
Accordingly, studies are being conducted on use of thin film materials formed on base materials (see Non patent Citation 2 and patent Citations 1 to 3, for example). For example, a light control device is proposed which includes a structure provided with polarizers on both sides of a display substrate on which PLZT films or the like are formed as thin-film materials having the electro-optic effect instead of the bulk PLZT. The electrode terminal portions of individual pixels of the display substrate are connected to an external drive circuit, and desired pixels are individually driven to provide a desired display with penetrating light from a light source provided on one side of the display substrate.    [Non patent Citation 1] J. Thomas Cutchen, et al., “Applied Optics vol. 14 No. 8”, August 1975, p. 1866-1873    [Non patent Citation 2] “Ferroelectric Memory Advanced Process”, 1st ed., Science Forum Inc., 13 Sep. 1999, p. 151-157    [Patent Citation 1] Japanese Patent Laid-open Publication No. 2007-146657    [Patent Citation 2] Japanese Patent Laid-open Publication No. 2005-294308    [Patent Citation 3] Japanese Patent Laid-open Publication No. 2006-154145